A coffin cover is draped with the Russian flag during a funeral, attended by thousands, for five pro-Russian activists, Saturday, May 24, 2014, in the town of Stakhanov, eastern Ukraine. Five insurgents killed in a battle with Ukrainian forces near the city of Luhansk were buried on Saturday. The clash is one of several firefights between the two sides that have left at least 20 dead and some 300 injured, according to the Ukrainian Defense Ministry, days ahead of the country’s presidential elections. (AP Photo/Vadim Ghirda)

A coffin cover is draped with the Russian flag during a funeral, attended by thousands, for five pro-Russian activists, Saturday, May 24, 2014, in the town of Stakhanov, eastern Ukraine. Five insurgents killed in a battle with Ukrainian forces near the city of Luhansk were buried on Saturday. The clash is one of several firefights between the two sides that have left at least 20 dead and some 300 injured, according to the Ukrainian Defense Ministry, days ahead of the country’s presidential elections. (AP Photo/Vadim Ghirda)

A pro-Russian armed militant with a sticker which reads “Donetsk People Republic,” guards a checkpoint blocking the major highway which links Kharkiv, outside Slovyansk, Ukraine, Saturday, May 24, 2014. Ukrainians vote Sunday in an early presidential election that could be a crucial step toward resolving the country’s crisis, but separatists in the east are threatening to block the vote. The election, which comes six months after the outbreak of protests that led to the president’s ouster and a deepening chasm between pro-Europe and pro-Russia Ukrainians, aims to unify the fiercely divided country or at least discourage further polarization.(AP Photo/Alexander Zemlianichenko)

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KIEV, Ukraine (AP) â€” Ukrainians are casting ballots Sunday in a presidential election seen as essential for stabilizing the country rocked by a deadly uprising in the east, where pro-Russia rebels have vowed to block the ballot.

The vote is held three months after the ouster of the country’s pro-Russia leader, who was chased from power by months of protests triggered by his decision to reject an association agreement with the European Union and keep close ties with Moscow.

Polls have shown billionaire candy-maker Petro Poroshenko far ahead of 20 other candidates, but short of the absolute majority needed to win in the first round, so a runoff set for June 15 is expected. Poroshenko’s nearest challenger is Yulia Tymoshenko, the divisive former prime minister who is far behind.

Vera Potemkina, 65, a retired university professor in Kiev, said she cast her ballot for Poroshenko because she hopes he will steer Ukraine out of Russia’s orbit and closer to the West. “We are part of Europe, we do not need Asia,” she said.

Another Kiev resident, 83-year old Mykhailo Matsko, said he also voted for Poroshenko. “Even though he is an oligarch, I still voted for him because the country must be united in such a difficult time and have a strong leadership.”

Sunday’s ballot is taking place despite deadly fighting in the east, where pro-Russia insurgents have seized government buildings and are clashing with government forces. The rebels, who have declared two sprawling regions of Donetsk and Luhansk independent, have said they wouldn’t allow the vote, which they described as an election in “a neighboring country.”

Ukraine’s deputy interior minister, Serhiy Yarovyi, said Saturday that police are ready to ensure order and security at polling stations in just nine of the 34 electoral districts in the east.

The interim Kiev government and the West are accusing Russia of backing the uprising after it annexed Ukraine’s Crimean Peninsula in March. Moscow has denied the accusations.

Russian President Vladimir Putin on Friday said the Kremlin would “respect the choice of the Ukrainian people” and would be ready to work with the winner, in an apparent bid to ease the worst crisis in relations with the West since the Cold War and avoid a new round of Western sanctions.

Ukraine’s acting prime minister, Arseniy Yatsenyuk, said in a televised address late Friday that the election will be the first step to stabilize the situation in the east.

“I would like to assure all my compatriots in the Donetsk and Luhansk regions who will be prevented from going to the polling stations by the war waged on Ukraine: The criminals don’t have much time left to terrorize our land,” Yatsenyuk said.